Reader communication with contact lens sensors and display device

ABSTRACT

A reader for communicating with both an eye-mountable device and a display device is provided. The reader can transmit radio frequency power to a tag that is part of the eye-mountable device. The reader can communicates with the tag using a first protocol. Communicating with the tag can include having the reader request data from the tag and receive the requested data from the tag. The reader can process the received data. The reader can store the processed data. The reader can communicates with the display device using a second protocol, where the first and second protocols can differ. Communicating with the display device can include having the reader transmit the stored data to the display device. The display device can receive the transmitted data, process the transmitted data, and generate one or more displays including the transmitted and/or processed data.

BACKGROUND

Unless otherwise indicated herein, the materials described in thissection are not prior art to the claims in this application and are notadmitted to be prior art by inclusion in this section.

An electrochemical amperometric sensor measures a concentration of ananalyte by measuring a current generated through electrochemicaloxidation or reduction reactions of the analyte at a working electrodeof the sensor. A reduction reaction occurs when electrons aretransferred from the electrode to the analyte, whereas an oxidationreaction occurs when electrons are transferred from the analyte to theelectrode. The direction of the electron transfer is dependent upon theelectrical potentials applied to the working electrode. A counterelectrode and/or reference electrode is used to complete a circuit withthe working electrode and allow the generated current to flow. When theworking electrode is appropriately biased, the output current can beproportional to the reaction rate, so as to provide a measure of theconcentration of the analyte surrounding the working electrode.

In some examples, a reagent is localized proximate the working electrodeto selectively react with a desired analyte. For example, glucoseoxidase can be fixed near the working electrode to react with glucoseand release hydrogen peroxide, which is then electrochemically detectedby the working electrode to indicate the presence of glucose. Otherenzymes and/or reagents can be used to detect other analytes.

SUMMARY

One aspect of the present disclosure provides a method. A readertransmits radio frequency power to a tag. The tag is part of aneye-mountable device. The reader communicates with the tag using a firstprotocol. Communicating with the tag includes: requesting data from thetag and receiving the requested data from the tag. The reader processesthe received data. The reader stores the processed data. The readercommunicates with a display device using a second protocol.Communicating with the display device includes transmitting the storeddata to the display device. The first protocol differs from the secondprotocol.

Another aspect of the present disclosure provides a non-transitorycomputer-readable storage medium. The non-transitory computer-readablestorage medium has stored thereon program instructions that, uponexecution by a processor of a computing device, cause the computingdevice to perform functions. The functions include: transmitting radiofrequency (RF) power to a tag, where the tag is part of an eye-mountabledevice, communicating with the tag using a first protocol, wherecommunicating with the tag includes requesting data from the tag andreceiving the requested data from the tag; processing the received datafrom the tag; storing the processed data; and communicating with adisplay device using a second protocol, where communicating with thedisplay device includes transmitting the stored data to the displaydevice, and where the first protocol differs from the second protocol.

Yet another aspect of the present disclosure provides a computingdevice. The computing device includes an antenna, a processor, and anon-transitory computer readable medium. The non-transitory computerreadable medium stores instructions thereon that, when executed by theprocessors, cause the computing device to perform functions. Thefunctions include: transmitting radio frequency (RF) power to a tagusing the antenna, where the tag is part of an eye-mountable device,communicating with the tag using a first protocol, where communicatingwith the tag includes requesting data from the tag and receiving therequested data from the tag; processing the received data from the tag;storing the processed data; and communicating with a display deviceusing a second protocol, where communicating with the display deviceincludes transmitting the stored data to the display device, and wherethe first protocol differs from the second protocol.

These as well as other aspects, advantages, and alternatives, willbecome apparent to those of ordinary skill in the art by reading thefollowing detailed description, with reference where appropriate to theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an example system that includes aneye-mountable device in wireless communication with a reader, inaccordance with an example embodiment.

FIG. 2A is a bottom view of an example eye-mountable device, inaccordance with an example embodiment.

FIG. 2B is a side view of the example eye-mountable device shown in FIG.2A, in accordance with an example embodiment.

FIG. 2C is a side cross-section view of the example eye-mountable deviceshown in FIGS. 2A and 2B while mounted to a corneal surface of an eye.

FIG. 2D is a side cross-section view enhanced to show the tear filmlayers surrounding the surfaces of the example eye-mountable device whenmounted as shown in FIG. 2C, in accordance with an example embodiment.

FIG. 3 is a functional block diagram of an example system forelectrochemically measuring a tear film analyte concentration, inaccordance with an example embodiment.

FIG. 4A is a block diagram of an ophthalmic electrochemical sensorsystem operated by a reader to obtain a series of amperometric currentmeasurements over time, in accordance with an example embodiment.

FIG. 4B is a block diagram of the ophthalmic electrochemical sensorsystem described in connection with FIG. 4A, in accordance with anexample embodiment.

FIG. 5 shows an example wearer wearing two eye-mountable devices, aband, earrings, and a necklace, in accordance with an exampleembodiment.

FIG. 6 shows a scenario where a reader communicates with aneye-mountable device and a display device, in accordance with an exampleembodiment.

FIGS. 7A-7E show example views of a user interface for a display device,in accordance with an example embodiment.

FIG. 8 is a flow chart of an example method, in accordance with anexample embodiment.

DETAILED DESCRIPTION

I. Overview

An ophthalmic sensing platform or implantable sensing platform caninclude a sensor, control electronics and an antenna all situated on asubstrate embedded in a polymeric material. The polymeric material canbe incorporated in an ophthalmic device, such as an eye-mountable deviceor an implantable medical device. The control electronics can operatethe sensor to perform readings and can operate the antenna to wirelesslycommunicate the readings from the sensor to a reader via the antenna.

In some examples, the polymeric material can be in the form of a roundlens with a concave curvature configured to mount to a corneal surfaceof an eye, such as a contact lens. The substrate can be embedded nearthe periphery of the polymeric material to avoid interference withincident light received closer to the central region of the cornea. Thesensor can be arranged on the substrate to face inward, toward thecorneal surface, so as to generate clinically relevant readings fromnear the surface of the cornea and/or from tear fluid interposed betweenthe polymeric material and the corneal surface. Additionally oralternatively, the sensor can be arranged on the substrate to faceoutward, away from the corneal surface and toward the layer of tearfluid coating the surface of the polymeric material exposed to theatmosphere. In some examples, the sensor is entirely embedded within thepolymeric material. For example, an electrochemical sensor that includesa working electrode and a reference electrode can be embedded in thepolymeric material and situated such that the sensor electrodes are lessthan 10 micrometers from the polymeric surface configured to mount tothe cornea. The sensor can generate an output signal indicative of aconcentration of an analyte that diffuses through the lens material tothe sensor electrodes.

Tear fluid contains a variety of inorganic electrolytes (e.g., Ca²⁺,Mg²⁺, Cl⁻), organic components (e.g., glucose, lactate, proteins,lipids, etc.), and so on that can be used to diagnose health states. Anophthalmic sensing platform including the above-mentioned sensor can beconfigured to measure one or more of these analytes can thus provide aconvenient non-invasive platform useful in diagnosing and/or monitoringhealth states. For example, an ophthalmic sensing platform can beconfigured to sense glucose and can be used by diabetic individuals tomeasure/monitor their glucose levels. In some embodiments, the sensorcan be configured to measure additional or other conditions other thananalyte levels; e.g., the sensor can be configured to such as light,temperature, and current measurements,

An external reader device or “reader” can radiate radio frequencyradiation to power the sensor. The reader may thereby control theoperation of the sensing platform by controlling the supply of power tothe sensing platform. In some examples, the reader can operate tointermittently interrogate the sensing platform to provide a reading byradiating sufficient radiation to power the sensing platform to obtain ameasurement and communicate the result. The reader can also store thesensor results communicated by the sensing platform. In this way, thereader can acquire a series of analyte concentration measurements overtime without continuously powering the sensing platform.

The sensor of the ophthalmic sensing platform can be configured with, orbe part of, a Radio-frequency Identification (RFID) tag. The RFID tagand reader can communicate using an RFID protocol; e.g., an RFIDGeneration 2 protocol. The RFID tag can be configured to receive radiosignals from the reader. In some embodiments, the reader's signals canbe used for both communicating with and powering the RFID tag; while inother embodiments, the RFID tag can be a powered device; e.g., beconfigured with a battery that powers the tag.

The reader can communicate with other devices than the RFID tag. As onepossible example, the reader can be equipped with a Bluetooth interfaceas well as with an RFID interface. The reader can communicate with otherdevices, e.g., a display device, via a Bluetooth or other protocol. Inone example, the reader can obtain data from the RFID tag using RFIDcommand(s); e.g., the RFID Generation 2 standard Read command. Uponobtaining the data, the reader can store, process, and/or communicatethe data using the Bluetooth interface to another device, such as thedisplay device. Other interfaces for communicating with devices usingother communication protocol(s) are possible as well.

As an example, the above-mentioned contact lens can be configured with asensor that includes an RFID tag. As mentioned above, the sensor can beconfigured to take measurements while being worn in an eye of a wearer.Upon taking the measurements, the sensor may store data related to themeasurements, and subsequently send the data upon request from thereader. The reader, in turn, can store and/or process the received data.For example, the sensor can take current measurements of an analyte(e.g., glucose) in tear film of the eye of the wearer and send dataabout the measured current(s) to the reader. The reader can process thecurrent measurement data to determine analyte-related information aboutthe wearer.

The tear-film analyte concentration information can be sent from thereader to a display device. The display device could be, for example, awearable, laptop, desktop, handheld, or tablet computer, a mobile phone,or a subsystem of such a device. The display device can include aprocessing system; e.g., a central processing unit (CPU), and anon-transitory computer readable medium configured to store at leastprogram instructions. One example of a wearable computer is ahead-mountable display (HMD). The HMD can be a device that is capable ofbeing worn on the head and places a display in front of one or both eyesof the wearer. The display device can store the data received from thereader, perhaps process the data, and generate display(s) based on thereceived and/or processed data.

In some embodiments, the reader and the display device can be configuredwith configuration data to perform glucose-related processing. Forexample, the reader can include configuration data such as currentmeasurement data for various levels of glucose concentration. Based onthis configuration data, the reader can determine a tear-film glucoseconcentration for the wearer. Also, the wearer can provide blood glucoseconcentration(s) and corresponding tear-film glucose concentration(s)for the wearer to the display device (for example, duringconfiguration), and the display device can determine relationshipsbetween blood glucose concentration(s) and tear-film glucoseconcentration(s).

During operation of these embodiments, the RFID tag in an eye of thewearer can generate tear-film current data and send the tear-filmcurrent data to the reader. The reader can then process the tear-filmcurrent data to generate tear-film glucose concentration(s) and send thetear-film glucose concentration(s) to the display device. Then, thedisplay device can be configured to receive tear-film glucoseconcentration(s) from the reader and generate corresponding bloodglucose concentration(s). In particular embodiments, either the readeror the display device can take tear-film current data as inputs andgenerate blood glucose concentration(s) as output(s); i.e., allprocessing can take place at either the reader or display device.

In some embodiments, the reader can be configured to be frequently wornin proximity to one or more contact lenses configured with sensors wornby a person. For example, the reader can be configured to be part of apair of eyeglasses, jewelry (e.g., earrings, necklace), headband, headcover such as a hat or cap, earpiece, other clothing (e.g., a scarf),and/or other devices. As such, the reader can provide power and/orreceive measurements while proximate to the worn contact lens(es).

Configuring the reader to be frequently worn in proximity to one or morecontact lenses enables the lenses to have a reliable external powersource and/or storage for sensor data collection, processing of sensordata, and transmission of unprocessed and/or processed sensor data toadditional devices; e.g., the above-mentioned display device. Thus, theherein-described reader can provide valuable support functionality,including but not limited to power, communication, and processingresources, to enhance use of contact lenses with embedded sensors, whileenabling consequent reduction of support functions on the contact lens.This reduction of support functions on the contact lens may freeresources on the contact lens to enable addition of more and/ordifferent sensors and to provide for other functionality on the contactlens.

II. Example Ophthalmic Electronics Platform

FIG. 1 is a block diagram of a system 100 that includes an eye-mountabledevice 110 in wireless communication with a reader 180. The exposedregions of the eye-mountable device 110 are made of a polymeric material120 formed to be contact-mounted to a corneal surface of an eye. Asubstrate 130 is embedded in the polymeric material 120 to provide amounting surface for a power supply 140, a controller 150,bio-interactive electronics 160, and a communication antenna 170. Thebio-interactive electronics 160 are operated by the controller 150. Thepower supply 140 supplies operating voltages to the controller 150and/or the bio-interactive electronics 160. The antenna 170 is operatedby the controller 150 to communicate information to and/or from theeye-mountable device 110. The antenna 170, the controller 150, the powersupply 140, and the bio-interactive electronics 160 can all be situatedon the embedded substrate 130. Because the eye-mountable device 110includes electronics and is configured to be contact-mounted to an eye,it is also referred to herein as an ophthalmic electronics platform.

To facilitate contact-mounting, the polymeric material 120 can have aconcave surface configured to adhere (“mount”) to a moistened cornealsurface (e.g., by capillary forces with a tear film coating the cornealsurface). Additionally or alternatively, the eye-mountable device 110can be adhered by a vacuum force between the corneal surface and thepolymeric material due to the concave curvature. While mounted with theconcave surface against the eye, the outward-facing surface of thepolymeric material 120 can have a convex curvature that is formed to notinterfere with eye-lid motion while the eye-mountable device 110 ismounted to the eye. For example, the polymeric material 120 can be asubstantially transparent curved polymeric disk shaped similarly to acontact lens.

The polymeric material 120 can include one or more biocompatiblematerials, such as those employed for use in contact lenses or otherophthalmic applications involving direct contact with the cornealsurface. The polymeric material 120 can optionally be formed in partfrom such biocompatible materials or can include an outer coating withsuch biocompatible materials. The polymeric material 120 can includematerials configured to moisturize the corneal surface, such ashydrogels and the like. In some embodiments, the polymeric material 120can be a deformable (“non-rigid”) material to enhance wearer comfort. Insome embodiments, the polymeric material 120 can be shaped to provide apredetermined, vision-correcting optical power, such as can be providedby a contact lens.

The substrate 130 includes one or more surfaces suitable for mountingthe bio-interactive electronics 160, the controller 150, the powersupply 140, and the antenna 170. The substrate 130 can be employed bothas a mounting platform for chip-based circuitry (e.g., by flip-chipmounting to connection pads) and/or as a platform for patterningconductive materials (e.g., gold, platinum, palladium, titanium, copper,aluminum, silver, metals, other conductive materials, combinations ofthese, etc.) to create electrodes, interconnects, connection pads,antennae, etc. In some embodiments, substantially transparent conductivematerials (e.g., indium tin oxide) can be patterned on the substrate 130to form circuitry, electrodes, etc. For example, the antenna 170 can beformed by forming a pattern of gold or another conductive material onthe substrate 130 by deposition, photolithography, electroplating, etc.Similarly, interconnects 151, 157 between the controller 150 and thebio-interactive electronics 160, and between the controller 150 and theantenna 170, respectively, can be formed by depositing suitable patternsof conductive materials on the substrate 130. A combination ofmicrofabrication techniques including, without limitation, the use ofphotoresists, masks, deposition techniques, and/or plating techniquescan be employed to pattern materials on the substrate 130. The substrate130 can be a relatively rigid material, such as polyethyleneterephthalate (“PET”) or another material configured to structurallysupport the circuitry and/or chip-based electronics within the polymericmaterial 120. The eye-mountable device 110 can alternatively be arrangedwith a group of unconnected substrates rather than a single substrate.For example, the controller 150 and a bio-sensor or otherbio-interactive electronic component can be mounted to one substrate,while the antenna 170 is mounted to another substrate and the two can beelectrically connected via the interconnects 157.

In some embodiments, the bio-interactive electronics 160 (and thesubstrate 130) can be positioned away from the center of theeye-mountable device 110 and thereby avoid interference with lighttransmission to the central, light-sensitive region of the eye. Forexample, where the eye-mountable device 110 is shaped as aconcave-curved disk, the substrate 130 can be embedded around theperiphery (e.g., near the outer circumference) of the disk. In someembodiments, however, the bio-interactive electronics 160 (and thesubstrate 130) can be positioned in or near the central region of theeye-mountable device 110. Additionally or alternatively, thebio-interactive electronics 160 and/or substrate 130 can besubstantially transparent to incoming visible light to mitigateinterference with light transmission to the eye. Moreover, in someembodiments, the bio-interactive electronics 160 can include a pixelarray 164 that emits and/or transmits light to be received by the eyeaccording to display instructions. Thus, the bio-interactive electronics160 can optionally be positioned in the center of the eye-mountabledevice so as to generate perceivable visual cues to a wearer of theeye-mountable device 110, such as by displaying information (e.g.,characters, symbols, flashing patterns, etc.) on the pixel array 164.

The substrate 130 can be shaped as a flattened ring with a radial widthdimension sufficient to provide a mounting platform for the embeddedelectronics components. The substrate 130 can have a thicknesssufficiently small to allow the substrate 130 to be embedded in thepolymeric material 120 without influencing the profile of theeye-mountable device 110. The substrate 130 can have a thicknesssufficiently large to provide structural stability suitable forsupporting the electronics mounted thereon. For example, the substrate130 can be shaped as a ring with a diameter of about 10 millimeters, aradial width of about 1 millimeter (e.g., an outer radius 1 millimeterlarger than an inner radius), and a thickness of about 50 micrometers.The substrate 130 can optionally be aligned with the curvature of theeye-mounting surface of the eye-mountable device 110 (e.g., convexsurface). For example, the substrate 130 can be shaped along the surfaceof an imaginary cone between two circular segments that define an innerradius and an outer radius. In such an example, the surface of thesubstrate 130 along the surface of the imaginary cone defines aninclined surface that is approximately aligned with the curvature of theeye mounting surface at that radius.

The power supply 140 is configured to harvest ambient energy to powerthe controller 150 and bio-interactive electronics 160. For example, aradio-frequency energy-harvesting antenna 142 can capture energy fromincident radio radiation. Additionally or alternatively, solar cell(s)144 (“photovoltaic cells”) can capture energy from incoming ultraviolet,visible, and/or infrared radiation. Furthermore, an inertial powerscavenging system can be included to capture energy from ambientvibrations. The energy harvesting antenna 142 can optionally be adual-purpose antenna that is also used to communicate information to thereader 180. That is, the functions of the communication antenna 170 andthe energy harvesting antenna 142 can be accomplished with the samephysical antenna.

A rectifier/regulator 146 can be used to condition the captured energyto a stable DC supply voltage 141 that is supplied to the controller150. For example, the energy harvesting antenna 142 can receive incidentradio frequency radiation. Varying electrical signals on the leads ofthe antenna 142 are output to the rectifier/regulator 146. Therectifier/regulator 146 rectifies the varying electrical signals to a DCvoltage and regulates the rectified DC voltage to a level suitable foroperating the controller 150. Additionally or alternatively, outputvoltage from the solar cell(s) 144 can be regulated to a level suitablefor operating the controller 150. The rectifier/regulator 146 caninclude one or more energy storage devices to mitigate high frequencyvariations in the ambient energy gathering antenna 142 and/or solarcell(s) 144. For example, one or more energy storage devices (e.g., acapacitor, an inductor, etc.) can be connected in parallel across theoutputs of the rectifier 146 to regulate the DC supply voltage 141 andconfigured to function as a low-pass filter.

The controller 150 is turned on when the DC supply voltage 141 isprovided to the controller 150, and the logic in the controller 150operates the bio-interactive electronics 160 and the antenna 170. Thecontroller 150 can include logic circuitry configured to operate thebio-interactive electronics 160 so as to interact with a biologicalenvironment of the eye-mountable device 110. The interaction couldinvolve the use of one or more components, such an analyte bio-sensor162, in bio-interactive electronics 160 to obtain input from thebiological environment. Additionally or alternatively, the interactioncould involve the use of one or more components, such as pixel array164, to provide an output to the biological environment.

In one example, the controller 150 includes a sensor interface module152 that is configured to operate analyte bio-sensor 162. The analytebio-sensor 162 can be, for example, an amperometric electrochemicalsensor that includes a working electrode and a reference electrode. Avoltage can be applied between the working and reference electrodes tocause an analyte to undergo an electrochemical reaction (e.g., areduction and/or oxidation reaction) at the working electrode. Theelectrochemical reaction can generate an amperometric current that canbe measured through the working electrode. The amperometric current canbe dependent on the analyte concentration. Thus, the amount of theamperometric current that is measured through the working electrode canprovide an indication of analyte concentration. In some embodiments, thesensor interface module 152 can be a potentiostat configured to apply avoltage difference between working and reference electrodes whilemeasuring a current through the working electrode.

In some instances, a reagent can also be included to sensitize theelectrochemical sensor to one or more desired analytes. For example, alayer of glucose oxidase (“GOx”) proximal to the working electrode cancatalyze glucose oxidation to generate hydrogen peroxide (H₂O₂). Thehydrogen peroxide can then be electro-oxidized at the working electrode,which releases electrons to the working electrode, resulting in anamperometric current that can be measured through the working electrode.

${{glucose} + {O_{2}G}}\overset{Ox}{\rightarrow}{{H_{2}O_{2}} + {gluconolactone}}$H₂O₂ → 2H⁺ + O₂ + 2e⁻

The current generated by either reduction or oxidation reactions isapproximately proportionate to the reaction rate. Further, the reactionrate is dependent on the rate of analyte molecules reaching theelectrochemical sensor electrodes to fuel the reduction or oxidationreactions, either directly or catalytically through a reagent. In asteady state, where analyte molecules diffuse to the electrochemicalsensor electrodes from a sampled region at approximately the same ratethat additional analyte molecules diffuse to the sampled region fromsurrounding regions, the reaction rate is approximately proportionate tothe concentration of the analyte molecules. The current measured throughthe working electrode thus provides an indication of the analyteconcentration.

The controller 150 can optionally include a display driver module 154for operating a pixel array 164. The pixel array 164 can be an array ofseparately programmable light transmitting, light reflecting, and/orlight emitting pixels arranged in rows and columns. The individual pixelcircuits can optionally include liquid crystal technologies,microelectromechanical technologies, emissive diode technologies, etc.to selectively transmit, reflect, and/or emit light according toinformation from the display driver module 154. Such a pixel array 164can also optionally include more than one color of pixels (e.g., red,green, and blue pixels) to render visual content in color. The displaydriver module 154 can include, for example, one or more data linesproviding programming information to the separately programmed pixels inthe pixel array 164 and one or more addressing lines for setting groupsof pixels to receive such programming information. Such a pixel array164 situated on the eye can also include one or more lenses to directlight from the pixel array to a focal plane perceivable by the eye.

The controller 150 can also include a communication circuit 156 forsending and/or receiving information via the antenna 170. Thecommunication circuit 156 can optionally include one or moreoscillators, mixers, frequency injectors, etc. to modulate and/ordemodulate information on a carrier frequency to be transmitted and/orreceived by the antenna 170. In some examples, the eye-mountable device110 is configured to indicate an output from a bio-sensor by modulatingan impedance of the antenna 170 in a manner that is perceivable by thereader 180. For example, the communication circuit 156 can causevariations in the amplitude, phase, and/or frequency of backscatterradiation from the antenna 170, and such variations can be detected bythe reader 180.

The controller 150 is connected to the bio-interactive electronics 160via interconnects 151. For example, where the controller 150 includeslogic elements implemented in an integrated circuit to form the sensorinterface module 152 and/or display driver module 154, a patternedconductive material (e.g., gold, platinum, palladium, titanium, copper,aluminum, silver, metals, combinations of these, etc.) can connect aterminal on the chip to the bio-interactive electronics 160. Similarly,the controller 150 is connected to the antenna 170 via interconnects157.

It is noted that the block diagram shown in FIG. 1 is described inconnection with functional modules for convenience in description.However, embodiments of the eye-mountable device 110 can be arrangedwith one or more of the functional modules (“sub-systems”) implementedin a single chip, integrated circuit, and/or physical component. Forexample, while the rectifier/regulator 146 is illustrated in the powersupply block 140, the rectifier/regulator 146 can be implemented in achip that also includes the logic elements of the controller 150 and/orother features of the embedded electronics in the eye-mountable device110. Thus, the DC supply voltage 141 that is provided to the controller150 from the power supply 140 can be a supply voltage that is providedto components on a chip by rectifier and/or regulator components locatedon the same chip. That is, the functional blocks in FIG. 1 shown as thepower supply block 140 and controller block 150 need not be implementedas physically separated modules. Moreover, one or more of the functionalmodules described in FIG. 1 can be implemented by separately packagedchips electrically connected to one another.

Additionally or alternatively, the energy harvesting antenna 142 and thecommunication antenna 170 can be implemented with the same physicalantenna. For example, a loop antenna can both harvest incident radiationfor power generation and communicate information via backscatterradiation.

The reader 180 can be configured to be external to the eye; i.e., is notpart of the eye-mountable device. Reader 180 can include one or moreantennae 188 to send and receive wireless signals 171 to and from theeye-mountable device 110. In some embodiments, reader 180 cancommunicate using hardware and/or software operating according to one ormore standards, such as, but not limited to, a RFID standard, aBluetooth standard, a Wi-Fi standard, a Zigbee standard, etc.

Reader 180 can also include a computing system with a processor 186 incommunication with a memory 182. Memory 182 is a non-transitorycomputer-readable medium that can include, without limitation, magneticdisks, optical disks, organic memory, and/or any other volatile (e.g.RAM) or non-volatile (e.g. ROM) storage system readable by the processor186. The memory 182 can include a data storage 183 to store indicationsof data, such as sensor readings (e.g., from the analyte bio-sensor162), program settings (e.g., to adjust behavior of the eye-mountabledevice 110 and/or reader 180), etc. The memory 182 can also includeprogram instructions 184 for execution by the processor 186 to cause thereader 180 to perform processes specified by the instructions 184. Forexample, the program instructions 184 can cause reader 180 to provide auser interface that allows for retrieving information communicated fromthe eye-mountable device 110 (e.g., sensor outputs from the analytebio-sensor 162). The reader 180 can also include one or more hardwarecomponents for operating the antenna 188 to send and receive thewireless signals 171 to and from the eye-mountable device 110. Forexample, oscillators, frequency injectors, encoders, decoders,amplifiers, filters, etc. can drive the antenna 188 according toinstructions from the processor 186.

In some embodiments, reader 180 can be a smart phone, digital assistant,or other portable computing device with wireless connectivity sufficientto provide the wireless communication link 171. In other embodiments,reader 180 can be implemented as an antenna module that can be pluggedin to a portable computing device; e.g., in scenarios where thecommunication link 171 operates at carrier frequencies not commonlyemployed in portable computing devices. In even other embodimentsdiscussed below in more detail in the context of at least FIG. 5, thereader 180 can be a special-purpose device configured to be wornrelatively near a wearer's eye to allow the wireless communication link171 to operate with a low power budget. For example, the reader 180 canbe integrated in a piece of jewelry such as a necklace, earring, etc. orintegrated in an article of clothing worn near the head, such as a hat,headband, etc.

In an example where the eye-mountable device 110 includes an analytebio-sensor 162, the system 100 can be operated to monitor the analyteconcentration in tear film on the surface of the eye. Thus, theeye-mountable device 110 can be configured as a platform for anophthalmic analyte bio-sensor. The tear film is an aqueous layersecreted from the lacrimal gland to coat the eye. The tear film is incontact with the blood supply through capillaries in the structure ofthe eye and includes many biomarkers found in blood that are analyzed tocharacterize a person's health condition(s). For example, the tear filmincludes glucose, calcium, sodium, cholesterol, potassium, otherbiomarkers, etc. The biomarker concentrations in the tear film can besystematically different than the corresponding concentrations of thebiomarkers in the blood, but a relationship between the twoconcentration levels can be established to map tear film biomarkerconcentration values to blood concentration levels. For example, thetear film concentration of glucose can be established (e.g., empiricallydetermined) to be approximately one tenth the corresponding bloodglucose concentration. Although another ratio relationship and/or anon-ratio relationship may be used. Thus, measuring tear film analyteconcentration levels provides a non-invasive technique for monitoringbiomarker levels in comparison to blood sampling techniques performed bylancing a volume of blood to be analyzed outside a person's body.Moreover, the ophthalmic analyte bio-sensor platform disclosed here canbe operated substantially continuously to enable real time monitoring ofanalyte concentrations.

To perform a reading with the system 100 configured as a tear filmanalyte monitor, the reader 180 can emit radio frequency radiation 171that is harvested to power the eye-mountable device 110 via the powersupply 140. Radio frequency electrical signals captured by the energyharvesting antenna 142 (and/or the communication antenna 170) arerectified and/or regulated in the rectifier/regulator 146 and aregulated DC supply voltage 147 is provided to the controller 150. Theradio frequency radiation 171 thus turns on the electronic componentswithin the eye-mountable device 110. Once turned on, the controller 150operates the analyte bio-sensor 162 to measure an analyte concentrationlevel. For example, the sensor interface module 152 can apply a voltagebetween a working electrode and a reference electrode in the analytebio-sensor 162. The applied voltage can be sufficient to cause theanalyte to undergo an electrochemical reaction at the working electrodeand thereby generate an amperometric current that can be measuredthrough the working electrode. The measured amperometric current canprovide the sensor reading (“result”) indicative of the analyteconcentration. The controller 150 can operate the antenna 170 tocommunicate the sensor reading back to the reader 180 (e.g., via thecommunication circuit 156). The sensor reading can be communicated by,for example, modulating an impedance of the communication antenna 170such that the modulation in impedance is detected by the reader 180. Themodulation in antenna impedance can be detected by, for example,backscatter radiation from the antenna 170.

In some embodiments, the system 100 can operate to non-continuously(“intermittently”) supply energy to the eye-mountable device 110 topower the controller 150 and electronics 160. For example, radiofrequency radiation 171 can be supplied to power the eye-mountabledevice 110 long enough to carry out a tear film analyte concentrationmeasurement and communicate the results. For example, the supplied radiofrequency radiation can provide sufficient power to apply a potentialbetween a working electrode and a reference electrode sufficient toinduce electrochemical reactions at the working electrode, measure theresulting amperometric current, and modulate the antenna impedance toadjust the backscatter radiation in a manner indicative of the measuredamperometric current. In such an example, the supplied radio frequencyradiation 171 can be considered an interrogation signal from the reader180 to the eye-mountable device 110 to request a measurement. Byperiodically interrogating the eye-mountable device 110 (e.g., bysupplying radio frequency radiation 171 to temporarily turn the deviceon) and storing the sensor results (e.g., via the data storage 183), thereader 180 can accumulate a set of analyte concentration measurementsover time without continuously powering the eye-mountable device 110.

FIG. 2A is a bottom view of an example eye-mountable electronic device210 (or ophthalmic electronics platform). FIG. 2B is an aspect view ofthe example eye-mountable electronic device shown in FIG. 2A. It isnoted that relative dimensions in FIGS. 2A and 2B are not necessarily toscale, but have been rendered for purposes of explanation only indescribing the arrangement of the example eye-mountable electronicdevice 210. The eye-mountable device 210 is formed of a polymericmaterial 220 shaped as a curved disk. In some embodiments, eye-mountabledevice 210 can include some or all of the above-mentioned aspects ofeye-mountable device 110. In other embodiments, eye-mountable device 110can further include some or all of the herein-mentioned aspects ofeye-mountable device 210.

The polymeric material 220 can be a substantially transparent materialto allow incident light to be transmitted to the eye while theeye-mountable device 210 is mounted to the eye. The polymeric material220 can be a biocompatible material similar to those employed to formvision correction and/or cosmetic contact lenses in optometry, such aspolyethylene terephthalate (“PET”), polymethyl methacrylate (“PMMA”),polyhydroxyethylmethacrylate (“polyHEMA”), silicone hydrogels,combinations of these, etc. The polymeric material 220 can be formedwith one side having a concave surface 226 suitable to fit over acorneal surface of an eye. The opposite side of the disk can have aconvex surface 224 that does not interfere with eyelid motion while theeye-mountable device 210 is mounted to the eye. A circular outer sideedge 228 connects the concave surface 224 and convex surface 226.

The eye-mountable device 210 can have dimensions similar to a visioncorrection and/or cosmetic contact lenses, such as a diameter ofapproximately 1 centimeter, and a thickness of about 0.1 to about 0.5millimeters. However, the diameter and thickness values are provided forexplanatory purposes only. In some embodiments, the dimensions of theeye-mountable device 210 can be selected according to the size and/orshape of the corneal surface of the wearer's eye.

The polymeric material 220 can be formed with a curved shape in avariety of ways. For example, techniques similar to those employed toform vision-correction contact lenses, such as heat molding, injectionmolding, spin casting, etc. can be employed to form the polymericmaterial 220. While the eye-mountable device 210 is mounted in an eye,the convex surface 224 faces outward to the ambient environment whilethe concave surface 226 faces inward, toward the corneal surface. Theconvex surface 224 can therefore be considered an outer, top surface ofthe eye-mountable device 210 whereas the concave surface 226 can beconsidered an inner, bottom surface. The “bottom” view shown in FIG. 2Ais facing the concave surface 226. From the bottom view shown in FIG.2A, the outer periphery 222, near the outer circumference of the curveddisk is curved to extend out of the page, whereas the central region221, near the center of the disk is curved to extend into the page.

A substrate 230 is embedded in the polymeric material 220. The substrate230 can be embedded to be situated along the outer periphery 222 of thepolymeric material 220, away from the central region 221. The substrate230 does not interfere with vision because it is too close to the eye tobe in focus and is positioned away from the central region 221 whereincident light is transmitted to the eye-sensing portions of the eye.Moreover, the substrate 230 can be formed of a transparent material tofurther mitigate effects on visual perception.

The substrate 230 can be shaped as a flat, circular ring (e.g., a diskwith a centered hole). The flat surface of the substrate 230 (e.g.,along the radial width) is a platform for mounting electronics such aschips (e.g., via flip-chip mounting) and for patterning conductivematerials (e.g., via microfabrication techniques such asphotolithography, deposition, plating, etc.) to form electrodes,antenna(e), and/or interconnections. The substrate 230 and the polymericmaterial 220 can be approximately cylindrically symmetric about a commoncentral axis. The substrate 230 can have, for example, a diameter ofabout 10 millimeters, a radial width of about 1 millimeter (e.g., anouter radius 1 millimeter greater than an inner radius), and a thicknessof about 50 micrometers. However, these dimensions are provided forexample purposes only, and in no way limit the present disclosure. Thesubstrate 230 can be implemented in a variety of different form factors,similar to the discussion of the substrate 130 in connection with FIG. 1above.

A loop antenna 270, controller 250, and bio-interactive electronics 260are disposed on the embedded substrate 230. The controller 250 can be achip including logic elements configured to operate the bio-interactiveelectronics 260 and the loop antenna 270. The controller 250 iselectrically connected to the loop antenna 270 by interconnects 257 alsosituated on the substrate 230. Similarly, the controller 250 iselectrically connected to the bio-interactive electronics 260 by aninterconnect 251. The interconnects 251, 257, the loop antenna 270, andany conductive electrodes (e.g., for an electrochemical analytebio-sensor, etc.) can be formed from conductive materials patterned onthe substrate 230 by a process for precisely patterning such materials,such as deposition, photolithography, etc. The conductive materialspatterned on the substrate 230 can be, for example, gold, platinum,palladium, titanium, carbon, aluminum, copper, silver, silver-chloride,conductors formed from noble materials, metals, combinations of these,etc.

As shown in FIG. 2A, which is a view facing the convex surface 224 ofthe eye-mountable device 210, bio-interactive electronics 260 is mountedto a side of the substrate 230 facing the convex surface 224. Where thebio-interactive electronics 260 includes an analyte bio-sensor, forexample, mounting such a bio-sensor on the substrate 230 facing theconvex surface 224 allows the bio-sensor to sense analyte concentrationsin tear film through channel 272 (shown in FIGS. 2C and 2D) in thepolymeric material 220 to convex surface 224. In some embodiments, someelectronic components can be mounted on one side of the substrate 230,while other electronic components are mounted to the opposing side, andconnections between the two can be made through conductive materialspassing through the substrate 230.

The loop antenna 270 is a layer of conductive material patterned alongthe flat surface of the substrate to form a flat conductive ring. Insome instances, the loop antenna 270 can be formed without making acomplete loop. For instances, the loop antenna can have a cutout toallow room for the controller 250 and bio-interactive electronics 260,as illustrated in FIG. 2A. However, the loop antenna 270 can also bearranged as a continuous strip of conductive material that wrapsentirely around the flat surface of the substrate 230 one or more times.For example, a strip of conductive material with multiple windings canbe patterned on the side of the substrate 230 opposite the controller250 and bio-interactive electronics 260. Interconnects between the endsof such a wound antenna (e.g., the antenna leads) can then be passedthrough the substrate 230 to the controller 250.

FIG. 2C is a side cross-section view of the example eye-mountableelectronic device 210 while mounted to a corneal surface 22 of an eye10. FIG. 2D is a close-in side cross-section view enhanced to show thetear film layers 40, 42 surrounding the exposed surfaces 224, 226 of theexample eye-mountable device 210. It is noted that relative dimensionsin FIGS. 2C and 2D are not necessarily to scale, but have been renderedfor purposes of explanation only in describing the arrangement of theexample eye-mountable electronic device 210. For example, the totalthickness of the eye-mountable device can be about 200 micrometers,while the thickness of the tear film layers 40, 42 can each be about 10micrometers, although this ratio may not be reflected in the drawings.Some aspects are exaggerated to allow for illustration and facilitateexplanation.

The eye 10 includes a cornea 20 that is covered by bringing the uppereyelid 30 and lower eyelid 32 together over the top of the eye 10.Incident light is received by the eye 10 through the cornea 20, wherelight is optically directed to light sensing elements of the eye 10(e.g., rods and cones, etc.) to stimulate visual perception. The motionof the eyelids 30, 32 distributes a tear film across the exposed cornealsurface 22 of the eye 10. The tear film is an aqueous solution secretedby the lacrimal gland to protect and lubricate the eye 10. When theeye-mountable device 210 is mounted in the eye 10, the tear film coatsboth the concave and convex surfaces 224, 226 with an inner layer 40(along the concave surface 226) and an outer layer 42 (along the convexlayer 224). The tear film layers 40, 42 can be about 10 micrometers inthickness and together account for about 10 microliters.

The tear film layers 40, 42 are distributed across the corneal surface22 and/or the convex surface 224 by motion of the eyelids 30, 32. Forexample, the eyelids 30, 32 raise and lower, respectively, to spread asmall volume of tear film across the corneal surface 22 and/or theconvex surface 224 of the eye-mountable device 210. The tear film layer40 on the corneal surface 22 also facilitates mounting the eye-mountabledevice 210 by capillary forces between the concave surface 226 and thecorneal surface 22. In some embodiments, the eye-mountable device 210can also be held over the eye in part by vacuum forces against cornealsurface 22 due to the concave curvature of the eye-facing concavesurface 226.

As shown in the cross-sectional views in FIGS. 2C and 2D, the substrate230 can be inclined such that the flat mounting surfaces of thesubstrate 230 are approximately parallel to the adjacent portion of theconvex surface 224. As described above, the substrate 230 is a flattenedring with an inward-facing surface 232 (facing concave surface 226 ofthe polymeric material 220) and an outward-facing surface 234 (facingconvex surface 224). The substrate 230 can have electronic componentsand/or patterned conductive materials mounted to either or both mountingsurfaces 232, 234. As shown in FIG. 2D, the bio-interactive electronics260, controller 250, and conductive interconnect 251 are mounted on theoutward-facing surface 234 such that the bio-interactive electronics 260are facing convex surface 224.

The polymer layer defining the anterior side may be greater than 50micrometers thick, whereas the polymer layer defining the posterior sidemay be less than 150 micrometers. Thus, bio-interactive electronics 260may be at least 50 micrometers away from the convex surface 224 and maybe a greater distance away from the concave surface 226. However, inother examples, the bio-interactive electronics 260 may be mounted onthe inward-facing surface 232 of the substrate 230 such that thebio-interactive electronics 260 are facing concave surface 226. Thebio-interactive electronics 260 could also be positioned closer to theconcave surface 226 than the convex surface 224. With this arrangement,the bio-interactive electronics 160 can receive analyte concentrationsin the tear film 292 through the channel 272.

III. An Ophthalmic Electrochemical Analyte Sensor

FIG. 3 is a functional block diagram of a system 300 forelectrochemically measuring and displaying a tear film analyteconcentration. The system 300 includes an eye-mountable device 210 withembedded electronic components in communication with and powered byreader 180. Reader 180 can also be configured to communicate withdisplay device 350. Reader 180 and eye-mountable device 210 cancommunicate according to one communication protocol or standard, shownin FIG. 3 as Protocol 1, and reader 180 and display device 350 cancommunicate according to one communication protocol or standard, shownin FIG. 3 as Protocol 2. In some embodiments, Protocol 1 and Protocol 2are the same; while in other embodiments, Protocol 1 differs fromProtocol 2. In particular embodiments, Protocol 1 is an RFID protocoland Protocol 2 is either a Bluetooth protocol, Wi-Fi protocol, or ZigBeeprotocol. In other particular embodiments, Protocol 1 is either aBluetooth protocol, a Wi-Fi protocol, or a ZigBee protocol. In stillother particular embodiments, Protocol 2 is a wired protocol; such as,but not limited to, a Universal Serial Bus protocol, a Registered Jackprotocol (e.g., RJ-25), or a wired Local Area Network protocol (e.g.,Ethernet).

The eye-mountable device 210 includes an antenna 312 for capturing radiofrequency (RF) power 341 from the reader 180. In some embodiments, RFpower 341 and/or backscatter communication 343 can be provided inaccordance with a communications standard or protocol, such as Protocol1 shown in FIG. 3.

The eye-mountable device 210 includes rectifier 314, energy storage 316,and regulator 318 for generating power supply voltages 330, 332 tooperate the embedded electronics. The eye-mountable device 210 includesan electrochemical sensor 320 with a working electrode 322 and areference electrode 323 driven by a sensor interface 321. Theeye-mountable device 210 includes hardware logic 324 for communicatingresults from the sensor 320 to the reader 180 by modulating theimpedance of the antenna 312. An impedance modulator 325 (shownsymbolically as a switch in FIG. 3) can be used to modulate the antennaimpedance according to instructions from the hardware logic 324. Similarto the eye-mountable device 110 discussed above in connection with FIG.1, the eye-mountable device 210 can include a mounting substrateembedded within a polymeric material configured to be mounted to an eye.

The electrochemical sensor 320 can be situated on a mounting surface ofsuch a substrate proximate the surface of the eye (e.g., correspondingto the bio-interactive electronics 260 on the inward-facing side 232 ofthe substrate 230) to measure analyte concentration in a tear film layerinterposed between the eye-mountable device 210 and the eye (e.g., theinner tear film layer 40 between the eye-mountable device 210 and thecorneal surface 22). In some embodiments, however, an electrochemicalsensor can be situated on a mounting surface of such a substrate distalthe surface of the eye (e.g., corresponding to the outward-facing side234 of the substrate 230) to measure analyte concentration in a tearfilm layer coating the exposed surface of the eye-mountable device 210(e.g., the outer tear film layer 42 interposed between the convexsurface 224 of the polymeric material 210 and the atmosphere and/orclosed eyelids).

With reference to FIG. 3, the electrochemical sensor 320 measuresanalyte concentration by applying a voltage between the electrodes 322,323 that is sufficient to cause products of the analyte catalyzed by thereagent to electrochemically react (e.g., a reduction and/or oxidizationreaction) at the working electrode 322. The electrochemical reactions atthe working electrode 322 generate an amperometric current that can bemeasured at the working electrode 322. The sensor interface 321 can, forexample, apply a reduction voltage between the working electrode 322 andthe reference electrode 323 to reduce products from thereagent-catalyzed analyte at the working electrode 322. Additionally oralternatively, the sensor interface 321 can apply an oxidization voltagebetween the working electrode 322 and the reference electrode 323 tooxidize the products from the reagent-catalyzed analyte at the workingelectrode 322. The sensor interface 321 measures the amperometriccurrent and provides an output to the hardware logic 324. The sensorinterface 321 can include, for example, a potentiostat connected to bothelectrodes 322, 323 to simultaneously apply a voltage between theworking electrode 322 and the reference electrode 323 and measure theresulting amperometric current through the working electrode 322.

In other embodiments, sensor 320 can further include and/or be replacedby sensor(s) that measure light, heat/temperature, blood pressure, airflow, and/or other characteristics than analyte concentration(s). Inthese other embodiments, sensor 320 can communicate data about themeasured characteristics to reader 180 using backscatter communication343 as discussed below.

The rectifier 314, energy storage 316, and voltage regulator 318 operateto harvest energy from received RF power 341. RF power 341 causes radiofrequency electrical signals on leads of the antenna 312. The rectifier314 is connected to the antenna leads and converts the radio frequencyelectrical signals to a DC voltage. The energy storage 316 (e.g.,capacitor) is connected across the output of the rectifier 314 to filterout high frequency components of the DC voltage. The regulator 318receives the filtered DC voltage and outputs both a digital supplyvoltage 330 to operate the hardware logic 324 and an analog supplyvoltage 332 to operate the electrochemical sensor 320. For example, theanalog supply voltage can be a voltage used by the sensor interface 321to apply a voltage between the sensor electrodes 322, 323 to generate anamperometric current. The digital supply voltage 330 can be a voltagesuitable for driving digital logic circuitry, such as approximately 1.2volts, approximately 3 volts, etc. Reception of the RF power 341 fromthe reader 180 (or another source, such as ambient radiation, etc.)causes the supply voltages 330, 332 to be supplied to the sensor 320 andhardware logic 324. While powered, the sensor 320 and hardware logic 324are configured to generate and measure an amperometric current andcommunicate the results.

The sensor results can be communicated back to the reader 180 viabackscatter radiation 343 from the antenna 312. The hardware logic 324receives the output current from the electrochemical sensor 320 andmodulates (325) the impedance of the antenna 312 in accordance with theamperometric current measured by the sensor 320. The antenna impedanceand/or change in antenna impedance are detected by the reader 180 viathe backscatter signal 343.

Reader 180 can include Protocol 1 front end 342 a and logic components344 to communicate using Protocol 1, decode the information indicated bythe backscatter signal 343, provide digital inputs to a processingsystem 346 and receive inputs and/or provide outputs via user interface348. Protocol 1 can be, for example, an RFID protocol. In someembodiments, part or all of eye-mountable device 210 can be configuredto perform some or all features of an RFID tag. For example, as shown inFIG. 3, some or all of the components shown as tag 370 of eye-mountabledevice 210 can perform some or all features of an RFID tag; e.g.,antenna 312, rectifier 314, energy storage 316, voltage regulator 318,hardware logic 324, etc.

In some embodiments, one or more of the features shown as separatefunctional blocks can be implemented (“packaged”) on a single chip. Forexample, the eye-mountable device 210 can be implemented with therectifier 314, energy storage 316, voltage regulator 318, sensorinterface 321, and the hardware logic 324 packaged together in a singlechip or controller module. Such a controller can have interconnects(“leads”) connected to the loop antenna 312 and the sensor electrodes322, 323. Such a controller operates to harvest energy received at theloop antenna 312, apply a voltage between the electrodes 322, 323sufficient to develop an amperometric current, measure the amperometriccurrent, and indicate the measured current via the antenna 312 (e.g.,through the backscatter radiation 343).

A processing system, such as, but not limited to, processing system 346or processing system 356, can include one or more processors and one ormore storage components. Example processor(s) include, but are notlimited to, CPUs, Graphics Processing Units (GPUs), digital signalprocessors (DSPs), application specific integrated circuits (ASICs).Example storage component(s) include, but are not limited to volatileand/or non-volatile storage components, e.g., optical, magnetic, organicor other memory, disc storage; Random Access Memory (RAM), Read-OnlyMemory (ROM), flash memory, optical memory unit, and disc memory. Thestorage component(s) can be configured to store software and data; e.g.,computer-readable instructions configured, when executed by a processorof the processing system, to cause the processing system to carry outfunctions such as but not limited to the herein-described functions ofreader 180, eye-mountable device 210, and/or display device 350.

The reader 180 can associate the backscatter signal 343 with the sensorresult (e.g., via the processing system 346 according to apre-programmed relationship associating impedance of the antenna 312with output from the sensor 320). The processing system 346 can thenstore the indicated sensor results (e.g., tear film analyteconcentration values) in a local memory and/or an external memory (e.g.,by communicating with the external memory either on display device 350or through a network).

User interface 348 of reader 180 can include an indicator, such as butnot limited to one or more light-emitting diodes (LEDs), that canindicate that reader 180 is operating and provide some information aboutits status. For example, reader 180 can be configured with an LED thatdisplays one color (e.g., green) when operating normally and anothercolor (e.g., red) when operating abnormally. In other embodiments, theLED(s) can change display when processing and/or communicating data incomparison to when idle (e.g., periodically turn on and off whileprocessing data, constantly stay on or constantly stay off while idle).

In some embodiments, one or more of the LED(s) of user interface 348 canindicate a status of sensor data; e.g., not display when sensor data areeither within normal range(s) or unavailable, display in a first colorwhen sensor data are either outside normal range(s) but not extremelyhigh or low, and display a second color when the sensor data areextremely high and/or low. For example, if sensor data indicate thatblood-glucose levels are extremely high or low, user interface 348 canbe instructed by processing system 346 to display using the secondcolor. In particular embodiments, user interface 348 can include aspeaker or other sound-emitting device to permit reader 180 to generatesounds; e.g., warning sound(s) and/or tone(s) if sensor data areextremely high and/or low.

In even other embodiments, reader 180 can have one or more buttonsand/or other devices to receive inputs. For example, reader 180 can havea calibration button to indicate when calibration data is to begenerated, such as discussed below in more detail in the context of atleast FIG. 6.

In some embodiments, reader 180 can communicate with devices in additionto eye-mountable device 210/tag 370. For example, FIG. 3 showscommunication 360 between reader 180 and display device 350 usingProtocol 2.

To communicate with display device 350, reader 180 can include Protocol2 front end 342 b and hardware logic 344 can be configured to useProtocol 2 front end 342 b to communicate using Protocol 2. In someembodiments, processing system 346 can be configured to include and/orperform the herein-described functionality of hardware logic 344.

FIG. 3 shows that display device 350 can include Protocol 2 front end352, hardware logic 354, processing system 356, and user interface (UI)358. Hardware logic 354 can be configured to use Protocol 2 front end352 to communicate using Protocol 2 with at least reader 180. Processingsystem 356 can include computer-readable instructions that, whenexecuted, are configured to perform some or all the herein-describedfunctions of display system 350. In some embodiments, processing system356 can be configured to include and/or perform the herein-describedfunctionality of hardware logic 354. UI 358 can be configured withhardware and/or software configured to present images, text, sound,haptic feedback, etc., such as, but not including, presenting images,text, audio, and/or video information related to data received fromreader 180 as part of communication 360. See FIGS. 7A-7E below forexample views that can be provided by display device 350.

In some embodiments, display device 350 can include Protocol 3 front end362. In these embodiments, hardware logic 354 can be configured to useProtocol 3 front end 362 to for sending and receiving communications 364using Protocol 3 with one or more other devices (not shown in FIG. 3).Protocol 3 can include one or more wireless protocols, such as, but notlimited to, a RFID protocol, a Bluetooth protocol, a Wi-Fi protocol, aZigBee protocol, a WiMax protocol, or a Wireless Wide Area Networkprotocol (e.g., TDMA, CDMA, GSM, UMTS, EV-DO, LTE) and/or one or morewired protocols; such as, but not limited to, a Universal Serial Busprotocol, a Registered Jack protocol (e.g., RJ-25), or a wired LocalArea Network protocol (e.g., Ethernet). In particular of theseembodiments, Protocol 2 front end 352 and Protocol 3 front end 362 canbe combined.

In embodiments utilizing Protocol 3, display device 350 can be used toforward and/or bridge data with the one or more other devices. Inparticular of these embodiments, a device of the one or more otherdevices can be a server configured to run one or more applications forcollecting data from display device 350; e.g., a cloud data collectionapplication.

IV. Example Electrochemical Sensor

FIG. 4A is a block diagram of a system 400 with eye-mountable device 210operated by a reader 180 to obtain a series of amperometric currentmeasurements over time. An ophthalmic electrochemical sensor; e.g., anembodiment of sensor 320, can be included with eye-mountable device 210.As shown in FIG. 4A, eye-mountable device 210 is configured to becontact-mounted over a corneal surface of an eye 10. The ophthalmicelectrochemical sensor can be operated to be transitioned into an activemeasurement mode in response to receiving a measurement signal from thereader 180.

The reader 180 includes a processing system 346, configured with memory414. The processing system 412 can be a computing system that executescomputer-readable instruction stored in the memory 414 to cause thereader 180/system 400 to obtain a time series of measurements byintermittently transmitting a measurement signal to eye-mountable device210. In response to the measurement signal, one or more sensors ofeye-mountable device 210; e.g., ophthalmic electrochemical sensor 430,can take measurement(s), obtain results of the measurement(s), andcommunicate the results as shown in connection to reader 180 viabackscatter 422. As discussed above regarding FIG. 3, reader 180 canprovide RF power, such as RF power 420, to be harvested by theeye-mountable device 210. For example, impedance of an antenna ofeye-mountable device 210 can be modulated in accordance with the sensorresult such that the backscatter radiation 422 indicates the sensorresults. Reader 180 can also use memory 414 to store indications ofamperometric current measurements communicated by the ophthalmicelectrochemical sensor 430. The reader 180 can thus be operated tointermittently power the ophthalmic electrochemical sensor 430 so as toobtain a time series of amperometric current measurements.

FIG. 4B is a block diagram of the ophthalmic electrochemical sensor 430described in connection with FIG. 4A. The ophthalmic electrochemicalsensor 430 can include stabilization electronics 432, measurementelectronics 434, an antenna 436, and sensor electrodes 438. Thestabilization electronics 432 can be configured to apply a stabilizationvoltage between the sensor electrodes 438 while the ophthalmicelectrochemical sensor 430 is operating in a standby (or stabilization)mode. The measurement electronics 434 are configured to measure theamperometric current through the working electrode of the sensorelectrodes 438 and communicate the measured amperometric current throughthe antenna 436.

Ophthalmic electrochemical sensor 430 can include energy harvestingsystems for harvesting energy from incident radiation (and/or othersources) to generate bias voltage to apply across sensor electrodesduring the standby mode. Ophthalmic electrochemical sensor 430 can alsobe configured to generate power from incident radiation to powermeasurement and communication electronics in response to receiving ameasurement signal indicating initiation of an active measurement mode.For example, measurement electronics 434 can be configured to harvestenergy from incident radio frequency radiation via the antenna 436 anduse the harvested energy to power the measurement and communication ofthe amperometric current.

V. Example Eye-Proximate Readers

FIG. 5 shows an example wearer 500 wearing two eye-mountable devices 210a, 210 b, a band 522, earrings 524 a, 524 b, and a necklace 526. Asdiscussed above at least in the context of FIGS. 3, 4A, and 4B, eacheye-mountable device 210 a, 210 b can be configured with sensor(s) tomeasure at least current in the tear-film of an eye that the respectivelens is worn in.

The functionality of band 522 can be performed by a structure of anotherdevice, e.g., an eye-glass frame, a head-mountable computer frame, acap, a hat, part of a hat or cap (e.g., a hat band or bill of a baseballcap), a headphone headband, etc., or by a separate band; e.g., a headband, a scarf or bandanna worn as a head band. For examples, band 522can be supported by ear(s), nose, hair, skin, and/or a head of wearer500, and perhaps by external devices e.g., stick pins, bobby pins,headband elastics, snaps. Other and different support(s) for band 522are possible as well.

One or more of band 522, earrings 524 a, 524 b, and necklace 526 can beconfigured to include one or more readers; e.g., the above-mentionedreader 180. FIG. 5 shows three example positions 180 a, 180 b, and 180 cfor readers in band 522. For example, if only eye-mountable device 210 ahas a sensor, then a reader, such as reader 180, can be mounted inexample positions 180 a and/or 180 b to send commands and power toeye-mountable device 210 a. Similarly, to power and communicate with asensor in eye-mountable device 210 b, a reader mounted in band 522, suchas reader 180, can be mounted in example positions 180 b and/or 180 c.

Each of or both earrings 524 a, 524 b can be configured with respectivereaders 180 d, 180 e for communicating with and power sensors inrespective eye-mountable devices 210 a, 210 b. Necklace 526 can beconfigured with one or more readers 180 f, 180 g, 180 h forcommunicating with and power sensors in respective eye-mountable device210 a, 210 b. Other embodiments are possible as well; e.g., readers inpositions 180 a-180 c or near those positions can be configured as partof a hat, headband, scarf, jewelry (e.g., a brooch), glasses, HMD,and/or other apparatus.

In some embodiments, a reader can power a sensor in eye-mountable device210 using a low-power transmission; e.g., a transmission of 1 watt orless of power. In these embodiments, the reader can be within apredetermined distance; e.g., 1 foot, 40 cm, of eye-mountable device 210a, 210 b to power the sensor.

FIG. 6 shows a scenario 600 where reader 180 communicates witheye-mountable device (EMD) 210 and display device 350. In scenario 600,eye-mountable device 210 and reader 180 communicate using an RFIDprotocol; e.g., an RFID Generation 2 protocol such as specified in “EPC™Radio-Frequency Identity Protocols Class-1 Generation-2 UHF RFIDProtocol for Communications at 860 MHz-960 MHz, Version 1.2.0”, Oct. 23,2008, EPCglobal Inc. In scenario 600, reader 180 and display device 350communicate via a Bluetooth protocol; e.g., a protocol such as specifiedin “Specification of the Bluetooth System”, Volumes 0-6, Core PackageVersion 4.0, Jun. 30, 2010, Bluetooth SIG, Inc.

In other scenarios, the reader, tag, display device, and/or otherdevice(s) can communicate using different and/or additional protocols;e.g., an IEEE 802.11 protocol (“Wi-Fi”), an IEEE 802.15 protocol(“Zigbee”), a Local Area Network (LAN) protocol, a Wireless Wide AreaNetwork (WWAN) protocol such as but not limited to a 2G protocol (e.g.,CDMA, TDMA, GSM), a 3G protocol (e.g., CDMA-2000, UMTS), a 4G protocol(e.g., LTE, WiMAX), a wired protocol (e.g., USB, a wired IEEE 802protocol, RS-232, DTMF, dial pulse). Many other examples of protocol(s)and combination(s) of protocols can be used as well.

Scenario 600 begins with reader 180 sending request tag ID message 620to eye-mountable device 210. In response to request tag ID message 620,eye-mountable device 210 can retrieve its identifier (ID) and send theID in receive tag ID message 222 to reader 180. In environments wheremultiple eye-mountable devices and/or other device(s) with tags areoperating, reader 180 can send a number of tag ID messages 620 to thedevices with operating tags to obtain IDs for all of the multipledevices with operating tags and responsively receive a number of receivetag ID messages 622. In some embodiments, one tag ID message 620 canlead to multiple receive tag ID messages 622 being sent; e.g., onereceive tag ID message from each of multiple devices with operatingtags. In scenario 600, only one device—eye mountable device 210—has anoperating tag and, thus, only one receive tag ID message 622 is receivedby reader 180 in response to request tag ID message 620.

Upon receiving the ID(s) (or other identifying information) foreye-mountable device 210, reader 180 can determine store the ID 624 anddetermine whether calibration data is available for the eye-mountabledevice. Some types of calibration data can be determined on a per-devicebasis; e.g., in scenario 600, calibration data for converting currentdata received from an analyte bio-sensor to concentration of the analytein tear-film can be determined on a per-device basis. For example, ananalyte bio-sensor configured to measure glucose can have calibrationdata to convert current data to tear-film glucose levels. Thecalibration data can be determined at time of manufacture of thebio-sensor; e.g., by taking current measurements using the bio-sensor(or equivalent device) in samples of liquids (e.g., water or artificialtear film) having different amounts of glucose dissolved in each liquidsample. Then, based on the measured current values, one or moremathematical models for converting current values to tear-film glucoselevels can be determined. Example mathematical models include, but arenot limited to, a linear model, a piecewise linear model, a quadraticmodel, a cubic model, a logarithmic model, an exponential model, oranother type of non-linear model. The mathematical model can take thecalibration data and current data as inputs and determine a tear-filmglucose model as output.

Other types of calibration data can be determined on a per-person orper-wearer basis; e.g., in scenario 600, calibration data for convertingtear-film glucose data to blood-glucose data can be determined on aper-wearer basis. This calibration data can be determined only after awearer (or person) has worn the bio-sensor and the calibration datadetermined. For example, to calibrate reader 180, a wearer ofeye-mountable sensor 210 can press a calibration button of reader 180shortly after finishing a meal so that reader 180 can determinerelatively high and relatively low blood-glucose levels for the wearer,and use those values as calibration data inputs to a mathematical modelfor converting current values and/or tear-film glucose levels toblood-glucose levels. The mathematical model can be one or more of theexample mathematical models listed above; e.g., a linear model, apiecewise linear model, etc. Other types of per-device and/or per-wearercalibration data are possible as well.

In scenario 600, reader 180 does not have calibration data foreye-mountable device 210 based on the ID provided in receive tag IDmessage 622. In response, reader 180 can generate one or more requestcalibration data messages 626 and receive, in response, one or morereceive calibration data messages 628. The request calibration datamessages 626 can include requests for one or more different types ofcalibration data; e.g., current to tear-film glucose calibration data,tear-film glucose to blood-glucose calibration data, data values forreader 180 to calculate calibration data. In scenario 600, reader 180provides some or all of the calibration data to display device 350 viasend calibration data message(s) 630 to permit display device 350 toperform some or all of the processing related to sensor data fromeye-mountable device 210. For example, reader 180 can use calibrationdata message(s) 630 to send calibration data to convert tear-filmglucose data received by reader 180 from an identified eye-mountabledevice to blood-glucose values, which display device 350 can thendisplay to the wearer of the identified eye-mountable device. In otherscenarios, display device 350 can send one or more request calibrationdata messages to reader 180 to request calibration data.

RFID tags, such as tag 370 of eye-mountable device 210, can be passivetags. A passive RFID tag can be configured to receive radio-frequency(RF) signals and to store power provided in the RF signals. The RFsignals may or may not include RFID messages. For example, reader 180can continuously send request tag ID messages to tag(s) within range ofreader 180 in order to provide power to the in-range tag(s); e.g., tag370. In some embodiments, reader 180 can send radio-frequency (RF)signals that are not RFID messages; e.g., a continuous RF waveform, toprovide periodic or continuous power to a tag. FIG. 6 shows an exampleof providing continuous power 632 from reader 180 to eye-mountabledevice 210.

Scenario 600 can continue with reader 180 sending request tag datamessage 640 to eye-mountable device 210 to obtain data fromeye-mountable device 210; e.g., data from one or more sensor(s) mountedon the contact lens and configured to communicate sensor data to thetag. Eye-mountable device 210 can provide the requested data in receivetag data message 642. Upon reception of the data from eye-mountabledevice 210, reader 180 can store the tag data 650 and/or process the tagdata 652, such as discussed in the glucose example above. Reader 180 canperiodically request data from eye-mountable device 210, such as bysending one or more request tag data messages 660 to eye-mountabledevice 210 and responsively receiving receive tag data message 662. Insome embodiments, reader 180 can determine if the contact lens hasenough power to operate the sensor and send tag data in response to arequest. For example, reader 180 can determine the power available toeye-mountable device 210 based on a determination of power provided byreader 180 to eye-mountable device 210, by measuring a signal strengthof message(s) received from eye-mountable device 210, by power-relateddata included in message(s) received from eye-mountable device 210,and/or by other techniques. Upon receiving tag data in receive tag datamessage 662, reader 180 can store the tag data 670 and/or process thetag data 672.

At some time, display device 350 can send request reader data message680 to reader 180 to request data from reader 180 and/or eye-mountabledevice 210. In some scenarios not shown in FIG. 6, upon reception ofrequest reader data message 680, reader 180 can send a request tag datamessage to obtain data from eye-mountable device 210 and subsequentlystore and/or process the data requested from eye-mountable device 210.After receiving request reader data message 680, reader 180 can generateand send receive reader data message 682 that includes data storedand/or processed by reader 180 to display device 350. In someembodiments, multiple messages may be used to perform the functionalityof receive reader data message 682 and/or any other message described inscenario 600. In some embodiments not shown in FIG. 6, reader 180 caninitiate data transmission to display device 350 when reader data isavailable, periodically, or using some other criteria; i.e., reader 180can push reader data to the display device.

After receiving data from reader 180 in receive reader data message 682,display device 350 can utilize reader data 690; e.g., process, present,store, communicate, and/or otherwise use reader data 690. For example,if reader data 690 includes tear-film glucose data, then display device350 can process the tear-film glucose data to generate blood-glucosedata. Upon generation of blood-glucose data, display device 350 canpresent the blood-glucose data using visual and/or audio means (e.g.,using display(s), speaker(s), bone conduction transducer(s), etc.).

In some embodiments, display device 350 can evaluate the blood-glucosedata. For example, display device 350 can compare blood-glucose data tolow-glucose and/or high-glucose threshold(s) to determine, respectively,whether the blood-glucose data is too high or low for wearer 100 ofeye-mountable device 210. If the blood-glucose data is too high or lowfor wearer 100, display device 350 can alert wearer 100, attempt tocontact another person or entity associated with wearer 100 to helpwearer 100, and/or perform some other action. As another example,display device 350 can have an interface with an insulin pump or similardevice configured to provide insulin to wearer 100. Then, if theblood-glucose data is too high, display device 100 can, via theinterface, instruct the insulin pump to provide insulin to wearer 100.Other examples are possible as well.

VI. Example Display Device Views

FIGS. 7A-7E show example views 710, 720, 730, 740, and 750 of a userinterface for a display device 350. Views 710, 720, 730, 740, and/or 750can be presented by one or more applications executing on display device350; e.g., a blood glucose meter and graph application. The displaydevice can be configured to display blood glucose levels, which can beor correspond to the blood-glucose data and/or blood glucoseconcentration values discussed above.

FIG. 7A shows example glucose meter view 710 indicating a “Normal” bloodglucose level of “5.0” measured using “mmol/L” values (millimoles perliter of blood). FIG. 7A shows view 710 with a background color of whiteto indicate a normal blood glucose level; other colors and/or patterns(e.g., green background for a traffic-light color scheme, a largewatermarked “OK”, a thumbs-up image) can be used instead of a whitebackground to designate a normal blood glucose level. View 710 indicatesthat a time of “9:18 PM” when the blood glucose level was measured and acurrent time of “9:20”. In some embodiments, audio data representingpart or all of the content of views 710, 720, 730, 740, and/or 750 canbe provided with or instead of the corresponding views; e.g., text suchas “Your Blood Glucose Level is 5.0 which is Normal” can be converted tospeech and presented using a speaker or similar audio-output device ofdisplay device 350.

View 710 also includes three buttons 712 a, 714, and 716 a. Button 712 amarked “Graph” can be configured to, when selected, instruct displaydevice 350 to draw a glucose graph, or graph of blood glucose levelsover time. Button 714 marked “Settings” can be configured to, whenselected, instruct display device 350 to display and/or enable changingof various settings related to the glucose meter and glucose graph.Button 716 a marked “mg/DL” can be configured to, when selected,instruct display device 350 to display blood glucose levels usingmilligrams of glucose per deciliter of blood (mg/DL) values. In someembodiments, the blood glucose meter and graph application can beterminated by selection of a button not shown in the Figures; e.g., aback or exit button.

FIG. 7B shows example glucose meter view 720 indicating an “Elevated”blood glucose level of “160.1” measured using “mg/DL” values. FIG. 7Bshows view 720 with a background color of grey to indicate an elevatedblood glucose level; other colors and/or patterns (e.g., yellowbackground for a traffic-light color scheme, a large watermarked“Warning”, an image of a warning sign) can be used instead of a greybackground to designate an elevated blood glucose level. View 720indicates that a time of “9:18 PM” when the blood glucose level wasmeasured and a current time of “9:20”. View 720 also includes button 716b marked “mmol/L”. Button 716 b can be configured to, when selected,instruct display device 350 to display blood glucose levels usingmillimole per liter (mmol/L) values.

FIG. 7C shows example glucose meter view 730 indicating an “Elevated”blood glucose level of “11.9” measured using “mmol/L” values. FIG. 7Cshows view 720 with a background color of black to indicate an elevatedblood glucose level; other colors and/or patterns (e.g., red backgroundfor a traffic-light color scheme, a large watermarked “Danger”, an imageof a siren or other emergency equipment) can be used instead of a blackbackground to designate a high blood glucose level. View 720 indicatesthat a time of “9:18 PM” when the blood glucose level was measured and acurrent time of “9:20”.

View 730 also includes buttons 732 a, 732 b each marked “Call Help”.Buttons 732 a and 732 b can each be configured to, when selected andwhen authorized by a person associated with display device 350, instructdisplay device 350 to originate a telephone call or other type ofmessage to a help number; e.g., an emergency services number (e.g.,911), spouse, other relative, friend, health service. For example, whenbutton 732 a is selected, a text message can be sent and/or a telephonecall can be originated to the help number. In some embodiments, thetelephone call can include at least an automated portion of the call. Instill other embodiments, the help number can include an e-mail address,and the call for help can include an e-mail to the e-mail addressincluded with the help number.

An example text/e-mail message or text for an automated (portion of a)telephone call can be “<P1> has a high blood glucose reading of <X><Y>and has asked you for help. Please assist!”, where <P1> can be replacedwith a name of a person associated with display device 350; e.g., theowner of display device 350, <X> can be replaced with the blood glucosereading value; e.g., 11.9 in view 730, and <Y> can be replaced with theunit measure used for the blood glucose reading value; e.g., mmol/L inview 730. In some embodiments, <P1> can be replaced or augmented by textrelated to a telephone directory number or other identifier (e.g.,device name, user name, Internet Protocol address) related to displaydevice 350; e.g., <P1> can be “<name>, who is associated with phonenumber <phoneno>,” or can be “The person associated with <phoneno>”,where <name> is the name of the person associated with display device350 and <phoneno> is the directory number associated with display device350.

In some embodiments, a call for help can be made automatically if bothauthorized by the person associated with display device 350 and theblood glucose level remains above a predetermined value for at least apredetermined amount of time. In other embodiments, views 710, 720, and730 can be used to display historical blood glucose levels; e.g., theblood glucose meter and graph application can display stored past bloodglucose levels for a given previous time or range of times.

FIG. 7D shows an example view with graph 740 of blood glucose levelsover one hour's time. Graph 740 has vertical axis 742 a for bloodglucose levels and horizontal axis 742 b for time. In the example shownin FIG. 7D, vertical axis 742 a shows blood glucose levels measured inmeasured in mmol/L and with a possible range from 5.0 to 6.5, andhorizontal axis 742 b shows time starting at 8:15 and ending at 9:15.FIG. 7D also shows display device 350 with a current time of 9:21.

Graph 740 includes a portion 744 a showing elevated blood glucoselevels, depicted as a grey band, and portion 744 b showing normal bloodglucose levels, depicted as a white band. Data region 746 of graph 740shows a maximum blood glucose level of “6.18” at a time of “8:33” andminimum blood glucose level of “5.03” at a time of “8:15”. In someembodiments not shown in FIG. 7D, a current and/or average blood glucoselevel can be displayed a part of data region 746 or in another portionof graph 740. In other embodiments not shown in FIG. 7D, a graphicaldisplay; e.g., a thermometer-style display, can be used to show minimum,maximum, current, average, and/or other specific blood glucose levels.

FIG. 7D shows the view with button 712 b marked “Meter”, which can beconfigured to, when selected, instruct display device 350 to display aglucose meter; e.g., display one of views 710, 720, or 730. FIG. 7Dshows the view with button 748 marked “Refresh”. Button 748 can beconfigured to, when selected, instruct display device 350 to refreshgraph 740, or re-display graph 740 using data most recently received;e.g., from reader 180.

FIG. 7E shows a “Glucose Meter Settings” view 750 for reviewing and/orchanging values related to the blood glucose meter and graphapplication. FIG. 7E shows view 750 with measurement setting 752, callfor help settings 752, 754, 756, 758, and 760, graph settings 762-770 c,and buttons 712 a, 712 b, 772, and 774. Measurement setting 752 can beused to select units of measurement for the blood glucose meter andgraph application; e.g., mmol/L or mg/dL.

Call for help setting 754 is configured to enable or disable the callfor help feature of the blood glucose meter and graph applicationdiscussed above in the context of at least FIG. 7C. FIG. 7E shows callfor help setting 754 with a check mark to indicate that the call forhelp feature is currently enabled. Automatic/manual setting 756 can beused to select whether calls for help are made automatically by displaydevice 350 e.g., upon detection of one or more conditions discussedabove in the context of FIG. 7C and without any intervention by aperson; or manually e.g., the call is made upon selection of a button,such as button 732 a or 732 b. Text/voice setting can be used to selectwhether calls for help are made using a text-based service e.g., textmessage or e-mail, and/or a voice-based service. In the example shown inFIG. 7C, calls for help will be made using only a voice-based service,as the “Text” setting is shown as not checked and the “Voice” setting isshown as checked. Help number 760 can be used to specify a number to usefor placing calls for help. In some embodiments not shown in FIG. 7E,help e-mail address(es) and/or multiple help numbers can be specified.

Graph duration setting 762 can be used to configure a duration for ablood glucose graph. In the example shown in FIG. 7E, one hour is used;while in other examples, shorter durations such as, but not limited to,15 or 30 minutes, can be selected, and in even other examples, longerdurations, such as, but not limited to, multiple hours, a day, ormultiple days can be selected. Glucose data storage setting 764 can beused to allocate an amount of storage used to store blood glucose datafor review and display. For example, if the data to store blood glucoselevels for one day is X megabytes, then selecting a glucose data storageof “1 week” as shown in FIG. 7A can cause display device 350 to allocateat least 7× megabytes for storing blood glucose levels.

Glucose range setting 766 can be used to select blood glucose valuescorresponding to a number of glucose level ranges. FIG. 7E shows fiveexample glucose level ranges: a high or hyperglycemic range, an elevatedrange, a normal range, a reduced range, and a low or hypoglycemic range.For example, FIG. 7E shows the elevated range bounded by lines 768 b and768 c, with line 768 b separating the hyperglycemic and elevated rangesassociated with blood glucose level 770 b of “10.1” mmol/L, and line 768c separating the elevated and normal ranges associated with bloodglucose level 770 c of “6.1” mmol/L. Mmol/L values are used by glucoserange setting 766 in accord with measurement setting 752. Thus, in thisexample, blood glucose levels between 6.1 and 10.1 mmol/L fall into theelevated range. As other examples, values between 10.1 mmol/L and amaximum blood glucose level 770 a; that is, values above 10.1 mmol/L,are in the hyperglycemic range, while values below 2.8 mmol/L are in thehypoglycemic range.

To change blood glucose level(s) associated with glucose range(s), auser of view 750 can use a touch screen or other input device to selecta line separating glucose ranges and then move the line up or downwithin glucose range setting 766. For example, if display device 350 isconfigured with a touch screen, a user can select line 770 b by touchinga portion of the screen display displaying line 770 b with a finger,stylus, or other selection indicator, and moving the selection indicatorup or down to adjust the range. In this example, a user can touch line770 b with a figure and move his or her finger up to change an upperbound of the elevated range from 10.1 to a higher value; e.g., 11.0mmol/L or move his or her finger down to change the upper bound of theelevated range to a lower value; e.g., 9.5 mmol/L.

Button 772 marked “Save” can be configured to, when selected, instructdisplay device 350 to save settings as indicated in glucose metersettings view 750. Button 775 marked “Exit” can be configured to, whenselected, instruct display device 350 to exit the glucose meter settingsview 750 and/or the blood glucose meter and graph application withoutsaving changed setting values.

VII. Example Operations

FIG. 8 is a flow chart of an example method 800. Method 800 can becarried out by a reader, such as reader 180, or a device that includes aprocessor, such part of processing system 346, with a computer readablemedium storing machine-readable instructions, where the machine-readableinstructions, when executed by the processor of the device, areconfigured to cause the device to carry out some or all of thetechniques described herein as method 800.

Method 800 can begin at block 810. At block 810, the reader can transmitRF power to a tag, such as discussed above in the context of at leastFIG. 6. The tag can be part of an eye-mountable device; e.g., tag 370 ofeye-mountable device 210, such as discussed above in more detail in thecontext of at least FIG. 3. In some embodiments, the reader can bewithin a predetermined distance from the tag when transmitting RF powerto the tag, such as discussed above in the context of at least FIG. 5.In other embodiments, the reader can be part of an HMD, such asdiscussed above in the context of at least FIG. 5.

At block 820, the reader can communicate with the tag using a firstprotocol. Communicating with the tag can include requesting data fromthe tag and receiving the requested data from the tag, such as discussedabove in the context of at least FIG. 6. In some embodiments,communicating with the tag can also include: sending a request for anidentifier (ID) of the tag using the first protocol and, in response tothe request for the ID of the tag, receiving a message that includes theID of the tag, such as discussed above at least in the context of FIG.6.

In other embodiments, requesting data from the tag can includerequesting one or more sensor measurements from the tag, such asdiscussed above at least in the context of FIG. 6. In still otherembodiments, the reader can transmit the RF power to the tag for atleast a predetermined period of time before requesting the one or moresensor measurements, such as discussed above at least in the context ofFIG. 6.

At block 830, the reader can process the data received from the tag,such as discussed above in the context of at least FIG. 6. In someembodiments, processing the received data can include determining atear-film glucose concentration based on the one or more sensormeasurements, such as discussed above in the context of at least FIG. 6.In particular embodiments, a blood glucose concentration can bedetermined based on the tear-film glucose concentration, such asdiscussed above in the context of at least FIGS. 1 and 6. In otherparticular embodiments, the display device can display the blood glucoseconcentration, such as discussed above in the context of at least FIGS.6 and 7.

At block 840, the reader can store the processed data, such as discussedabove in the context of at least FIG. 6.

At block 850, the reader can communicate with a display device using asecond protocol, such as discussed above in the context of at least FIG.6. Communicating with the display device can include transmitting thestored data to the display device. The first protocol can differ fromthe second protocol.

In some embodiments, communicating with the display device can includereceiving a request for the stored data from the display device, such asdiscussed above in the context of at least FIG. 6. In other embodiments,the first protocol can be a Radio-Frequency Identification (RFID)protocol, and the second protocol can be a Bluetooth protocol, such asdiscussed above in the context of at least FIGS. 3 and 6.

The present disclosure is not to be limited in terms of the particularembodiments described in this application, which are intended asillustrations of various aspects. Many modifications and variations canbe made without departing from its spirit and scope, as will be apparentto those skilled in the art. Functionally equivalent methods andapparatuses within the scope of the disclosure, in addition to thoseenumerated herein, will be apparent to those skilled in the art from theforegoing descriptions. Such modifications and variations are intendedto fall within the scope of the appended claims.

The above detailed description describes various features and functionsof the disclosed systems, devices, and methods with reference to theaccompanying figures. In the figures, similar symbols typically identifysimilar components, unless context dictates otherwise. The exampleembodiments described herein and in the figures are not meant to belimiting. Other embodiments can be utilized, and other changes can bemade, without departing from the spirit or scope of the subject matterpresented herein. It will be readily understood that the aspects of thepresent disclosure, as generally described herein, and illustrated inthe figures, can be arranged, substituted, combined, separated, anddesigned in a wide variety of different configurations, all of which areexplicitly contemplated herein.

With respect to any or all of the ladder diagrams, scenarios, and flowcharts in the figures and as discussed herein, each block and/orcommunication may represent a processing of information and/or atransmission of information in accordance with example embodiments.Alternative embodiments are included within the scope of these exampleembodiments. In these alternative embodiments, for example, functionsdescribed as blocks, transmissions, communications, requests, responses,and/or messages may be executed out of order from that shown ordiscussed, including substantially concurrent or in reverse order,depending on the functionality involved. Further, more or fewer blocksand/or functions may be used with any of the ladder diagrams, scenarios,and flow charts discussed herein, and these ladder diagrams, scenarios,and flow charts may be combined with one another, in part or in whole.

A block that represents a processing of information may correspond tocircuitry that can be configured to perform the specific logicalfunctions of a herein-described method or technique. Alternatively oradditionally, a block that represents a processing of information maycorrespond to a module, a segment, or a portion of program code(including related data). The program code may include one or moreinstructions executable by a processor for implementing specific logicalfunctions or actions in the method or technique. The program code and/orrelated data may be stored on any type of computer readable medium suchas a storage device including a disk or hard drive or other storagemedium.

The computer readable medium may also include non-transitory computerreadable media such as computer-readable media that stores data forshort periods of time like register memory, processor cache, and randomaccess memory (RAM). The computer readable media may also includenon-transitory computer readable media that stores program code and/ordata for longer periods of time, such as secondary or persistent longterm storage, like read only memory (ROM), optical or magnetic disks,compact-disc read only memory (CD-ROM), for example. The computerreadable media may also be any other volatile or non-volatile storagesystems. A computer readable medium may be considered a computerreadable storage medium, for example, or a tangible storage device.

Moreover, a block that represents one or more information transmissionsmay correspond to information transmissions between software and/orhardware modules in the same physical device. However, other informationtransmissions may be between software modules and/or hardware modules indifferent physical devices.

The particular arrangements shown in the figures should not be viewed aslimiting. It should be understood that other embodiments can includemore or less of each element shown in a given figure. Further, some ofthe illustrated elements can be combined or omitted. Yet further, anexample embodiment can include elements that are not illustrated in thefigures.

It will be readily understood that the aspects of the presentdisclosure, as generally described herein, and illustrated in thefigures, can be arranged, substituted, combined, separated, and designedin a wide variety of different configurations, all of which areexplicitly contemplated herein. While various aspects and embodimentshave been disclosed herein, other aspects and embodiments will beapparent to those skilled in the art.

Example methods and systems are described above. It should be understoodthat the words “example” and “exemplary” are used herein to mean“serving as an example, instance, or illustration.” Any embodiment orfeature described herein as being an “example” or “exemplary” is notnecessarily to be construed as preferred or advantageous over otherembodiments or features. Reference is made herein to the accompanyingfigures, which form a part thereof. In the figures, similar symbolstypically identify similar components, unless context dictatesotherwise. Other embodiments may be utilized, and other changes may bemade, without departing from the spirit or scope of the subject matterpresented herein. The various aspects and embodiments disclosed hereinare for purposes of illustration and are not intended to be limiting,with the true scope and spirit being indicated by the following claims.

What is claimed is:
 1. A method, comprising: transmitting, by a reader,radio frequency (RF) power to a tag, wherein the tag is part of a devicethat includes a bio-sensor; communicating with the tag, by the reader,using a first wireless protocol, wherein communicating with the tagcomprises: requesting data from the tag, and receiving the requesteddata from the tag; processing the received data from the tag at thereader to provide processed data, wherein the received data relates toone or more measurements obtained by the bio-sensor, and wherein theprocessed data comprises an analyte concentration determined based onthe one or more measurements and calibration data; storing the processeddata using the reader; and communicating with a display device, by thereader, using a second wireless protocol, wherein the communicating withthe display device comprises transmitting the stored data to the displaydevice, wherein the display device is a wearable computer, handheldcomputer, tablet computer, laptop computer, or mobile phone, and whereinthe first wireless protocol differs from the second wireless protocol.2. The method of claim 1, wherein communicating with the display devicecomprises receiving a request for the stored data from the displaydevice.
 3. The method of claim 1, wherein the reader is within apredetermined distance from the tag when transmitting RF power to thetag.
 4. The method of claim 1, wherein communicating with the tagfurther comprises: sending a request for an identifier (ID) of the tagusing the first wireless protocol; and in response to the request forthe ID of the tag, receiving a message comprising the ID of the tag. 5.The method of claim 1, wherein the received data relates to one or moreglucose measurements obtained by the bio-sensor.
 6. The method of claim5, wherein the analyte concentration is a tear-film glucoseconcentration.
 7. The method of claim 6, further comprising: determininga blood glucose concentration based on the tear-film glucoseconcentration.
 8. The method of claim 7, further comprising: displayingthe blood glucose concentration on the display device.
 9. The method ofclaim 1, wherein the reader transmits the RF power to the tag for atleast a predetermined period of time before requesting the data from thetag.
 10. The method of claim 1, wherein the first wireless protocol is aRadio-Frequency Identification (RFID) protocol, and wherein the secondwireless protocol is a Bluetooth protocol.
 11. The method of claim 1,wherein the device is an eye-mountable device, and wherein the reader ispart of a head-mountable device.
 12. A non-transitory computer-readablestorage medium having stored thereon program instructions that, uponexecution by a processor of a computing device, cause the computingdevice to perform functions comprising: transmitting radio frequency(RF) power to a tag, wherein the tag is part of a device that includes abio-sensor; communicating with the tag using a first wireless protocol,wherein communicating with the tag comprises: requesting data from thetag, and receiving the requested data from the tag; processing thereceived data from the tag to provide processed data, wherein thereceived data relates to one or more measurements obtained by thebio-sensor, and wherein the processed data comprises an analyteconcentration determined based on the one or more measurements andcalibration data; storing the processed data; and communicating with adisplay device using a second wireless protocol, wherein thecommunicating with the display device comprises transmitting the storeddata to the display device, wherein the display device is a wearablecomputer, handheld computer, tablet computer, laptop computer, or mobilephone, and wherein the first wireless protocol differs from the secondwireless protocol.
 13. The non-transitory computer-readable storagemedium of claim 12, wherein the computing device is within apredetermined distance from the tag when transmitting RF power to thetag.
 14. The non-transitory computer-readable storage medium of claim12, wherein the received data relates to one or more glucosemeasurements obtained by the bio-sensor, and wherein the analyteconcentration is a tear-film glucose concentration.
 15. Thenon-transitory computer-readable storage medium of claim 12, wherein thecomputing device transmits the RF power to the tag for at least apredetermined period of time before requesting the data from the tag.16. The non-transitory computer-readable storage medium of claim 12,wherein the first wireless protocol is a Radio-Frequency Identification(RFID) protocol, and wherein the second wireless protocol is a Bluetoothprotocol.
 17. A computing device, comprising: an antenna; a processor;and a non-transitory computer readable medium storing instructionsthereon that, when executed by the processor, cause the computing deviceto perform functions comprising: transmitting radio frequency (RF) powerto a tag using the antenna, wherein the tag is part of a device thatincludes a bio-sensor; communicating with the tag using a first wirelessprotocol, wherein communicating with the tag comprises: requesting datafrom the tag, and receiving the requested data from the tag; processingthe received data from the tag to provide processed data, wherein thereceived data relates to one or more measurements obtained by thebio-sensor, and wherein the processed data comprises an analyteconcentration determined based on the one or more measurements andcalibration data; storing the processed data; and communicating with adisplay device using a second wireless protocol, wherein communicatingwith the display device comprises transmitting the stored data to thedisplay device, wherein the display device is a wearable computer,handheld computer, tablet computer, laptop computer, or mobile phone,and wherein the first wireless protocol differs from the second wirelessprotocol.
 18. The computing device of claim 17, wherein the computingdevice is within a predetermined distance from the tag when transmittingRF power to the tag.
 19. The computing device of claim 18, wherein thereceived data relates to one or more glucose measurements obtained bythe bio-sensor, and wherein the analyte concentration is a tear-filmglucose concentration.
 20. The computing device of claim 18, furthercomprising at least one transceiver configured to communicate using atleast the first wireless protocol and the second wireless protocol,wherein the first wireless protocol is a Radio-Frequency Identification(RFID) protocol, and wherein the second wireless protocol is a Bluetoothprotocol.